In this study. we present a mathematical modelling and optimal control approach to formulate patient-specific drug-specific treatment strategies for HIV-infected patients. Central to this is the fact that no two individuals respond to infection and treatment in quite the same way, and that different drugs are associated with varied efficacies in the body as well as with different side-effects. We hereby present a methodology which allows optimal planning on a case-by-case basis, unlike previous work in the field which formulated treatment protocols for general use by considering drug efficacies only. Investigation of optimal strategies by using models which consider the pharmacokinetic behaviour of drugs as well as their side-effects by using a well-documented chart may be considered a novel contribution and allows for the optimum administration of all drugs depending on their degree of toxicity as well as their effectiveness in the body. The formulated model is able to replicate clinical data from different progressors to AIDS by estimation of immune system parameters only. The latter have been suggested to be key in determining the degree of progression and the ability of the model to reproduce this phenomenon further validates the formulation. Optimal treatment strategies are produced for different patients and we can conclude that a general treatment protocol cannot be proposed and therapy has to be designed on an individual basis. (C) 2009 Elsevier Ltd. All rights reserved.